Which is the stronger acid? Acetic Acid, or Formic Acid
2006-07-30 09:05:01 · 12 answers · asked by blynn 1 in Science & Mathematics ➔ Chemistry
Which is the stronger acid depends on the acid dissociation constant or the acidity constant, Ka.
HA(aq) = H+(aq) + A–(aq)
Ka = [H+] [A-]/[HA]
Another common way to express the Ka is logarithmically using:
pKa = -log(Ka)
For acetic acid, the pKa is 4.76
For formic acid, the pKa is 3.75
In general, a larger value of Ka (or a smaller value of pKa) indicates a stronger acid, since the extent of dissociation is larger at the same concentration.
So formic acid is a little stronger than acetic acid.
2006-07-30 09:54:49 · answer #1 · answered by Kitiany 5 · 1⤊ 0⤋
Formic Acid
2006-07-30 13:16:24 · answer #2 · answered by Takbir 1 · 0⤊ 0⤋
As those above me have said before, Formic Acid. To see why, think about which is more easily solvated. Formic Acid is a smaller molecule. In determining acidity, solvent effects play a major role especially in similar systems. It may be easy to say that the methyl group donates electron density in acetic acid and therefore destabilizes the negative charge on the oxygen of the acetate ion, but one must be careful. In the gas phase this argument would not stand well. It is thought that in the gas phase the methyl group is actually electron withdrawing. Electronic effects are very important, but in solution never forget the solvent.
2006-07-30 16:09:03 · answer #3 · answered by chemIST 1 · 0⤊ 0⤋
Formic acid is the stronger. Acetic acid does not ionize readily therefore it forms a weaker acid.
2006-07-30 11:37:41 · answer #4 · answered by physandchemteach 7 · 0⤊ 0⤋
Acetic acid Ph is 4.5 and formic acid ph is 1.8 therefore making it stronger. But overall its still a weak acid. Check on the Ph scale for more info. Hope this helps.
http://www2.iq.usp.br/docente/gutz/Curtipot_.html
2006-07-30 09:10:52 · answer #5 · answered by Prince O Zamunda 4 · 0⤊ 0⤋
I think... Formic Acid is stronger. Acetic Acid is pretty weak.
http://en.wikipedia.org/wiki/Formic_acid
http://en.wikipedia.org/wiki/Acetic_acid
2006-07-30 09:08:43 · answer #6 · answered by ♥ jojo ♥ 4 · 0⤊ 0⤋
formic acid is more acidic than acetic acid, u can check and verify that info to any literature
2006-07-30 09:36:51 · answer #7 · answered by pingz 3 · 0⤊ 0⤋
Formic acid is stronger....pH of formic asid is lower so it is stronger
2006-07-30 09:49:42 · answer #8 · answered by master_of_knowledge 1 · 0⤊ 0⤋
At a guess, formic.
The methyl group is more electron donating than a proton (look at things like hyperconjugation etc) so destablises the anion formed when the acid deprotonates.
Also see http://daecr1.harvard.edu/pdf/evans_pKa_table.pdf
2006-07-30 09:10:11 · answer #9 · answered by Stephan B 5 · 0⤊ 0⤋
formic as it dessociates almost completely when dissolved in water which us why has a PH of 1.7
acetic is weaker as very little of it dissociated when dissolved in water and has a PH of 4.9
2006-07-30 09:39:58 · answer #10 · answered by bz_co0l@rogers.com 3 · 0⤊ 0⤋